Field of the Invention
Embodiments of the present invention generally relate to a method and apparatus for measuring torque in a top drive system.
Description of the Related Art
A wellbore is formed to access hydrocarbon-bearing formations (e.g., crude oil and/or natural gas) or for geothermal power generation by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a drill string. To drill within the wellbore to a predetermined depth, the drill string is often rotated by a top drive on a surface rig. After drilling to a predetermined depth, the drill string and drill bit are removed and a section of casing is lowered into the wellbore. An annulus is thus formed between the string of casing and the formation. The casing string is hung from the wellhead. A cementing operation is then conducted in order to fill the annulus with cement. The casing string is cemented into the wellbore by circulating cement into the annulus defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
Top drives are equipped with a motor for rotating the drill string. The quill of the top drive is typically threaded for connection to an upper end of the drill pipe in order to transmit torque to the drill string. It is important to accurately measure the torque transmitted by the top drive to ensure proper engagement between the quill of the top drive and the drill string. Furthermore, the torque must be accurately measured to prevent overloading the drill string, drill head, and/or drill bit.
Therefore, there is a need for an apparatus and method for accurately measuring the torque provided by the top drive system.